Re: [hylafax-users] Asterisk+iaxmodem+Hylafax: Failure to receive silence (synchronization failure).

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Matias Rollan wrote:
> On Mon, Oct 18, 2010 at 08:30:37PM -0700, Lee Howard wrote:
>   
> > Matias Rollan wrote:
> >     
> > > I am trying to make iaxmodem+asterisk+hylafax to work together without 
> > > success, I get the error below and when calling from the PSTN the call is 
> > > not even answered (it keeps ringing till it ends) but in the asterisk side 
> > > I can see how the call is answered through the iax channel:
> > >
> > > ivr-virtual-101*CLI>
> > >    -- Executing [011NNNNNNNN@entrantes:1] Answer("SIP/1.2.3.4-0a096a70", 
> > >    "") in new stack
> > >    -- Executing [011NNNNNNNN@entrantes:2] Dial("SIP/1.2.3.4-0a096a70", 
> > >    "IAX2/125/011NNNNNNNN|15|r") in new stack
> > >       
> > I see SIP and not PSTN.  Please read:
> >
> > http://hylafax.sourceforge.net/docs/fax-over-voip.pdf
> >
> >     
> Yes, it is true but I have the following scenario where the only SIP connection is between two legs that are in a local network with no jitter/latency and G.711:
>
>  -- SS7 --> Cisco ---> SIP --> Asterisk
>
> "Cisco" and "Asterisk" are on the same local network and I am aware of the problems with faxing over IP.

Simply because two VoIP endpoints are on the same LAN does not by any 
means give you an assurance that there will be no dropped UDP packets in 
network communications between them.  What assurance do you have?

> Right now I am using app_rxfax as an Asterisk module but wanted to switch to Hylafax.
>
> What could it be the problem of not getting the call answer on the originator leg but seeing how asterisk generated the Dial() to IAXModem and hylafax picked up the call ?
> The originator leg (when calling from the PSTN to 011NNNNNNNN) keeps ringing till it hungs up.
>
> I should be able to get some faxes (even if the receiving is not 100% error free) or even get the fax signal with this scenario right?
>   

It sounds as if you're having some faxes get through with app_rxfax 
(with G.711 and not T.38, I presume).  Yes, you should be able to get 
similar (if not better) results with iaxmodem and HylaFAX as you do with 
app_rxfax.

Here's the log you provided:

> Oct 18 20:52:00.26: [ 9888]: <-- [4:ATA\r]
> Oct 18 20:52:03.98: [ 9888]: --> [7:CONNECT]
> Oct 18 20:52:03.98: [ 9888]: ANSWER: FAX CONNECTION  DEVICE '/dev/tty125'
> Oct 18 20:52:03.98: [ 9888]: RECV FAX: begin
> Oct 18 20:52:03.98: [ 9888]: <-- data [32]
> Oct 18 20:52:03.98: [ 9888]: <-- data [2]
> Oct 18 20:52:04.94: [ 9888]: --> [7:CONNECT]
> Oct 18 20:52:04.94: [ 9888]: <-- data [23]
> Oct 18 20:52:04.94: [ 9888]: <-- data [2]
> Oct 18 20:52:05.68: [ 9888]: --> [7:CONNECT]
> Oct 18 20:52:05.68: [ 9888]: <-- data [13]
> Oct 18 20:52:05.68: [ 9888]: <-- data [2]
> Oct 18 20:52:06.26: [ 9888]: --> [2:OK]
> Oct 18 20:52:06.26: [ 9888]: <-- [9:AT+FRH=3\r]
> Oct 18 20:52:13.26: [ 9888]: --> [0:]
> Oct 18 20:52:13.26: [ 9888]: MODEM <Empty line>
> Oct 18 20:52:13.26: [ 9888]: <-- data [1]
> Oct 18 20:52:13.28: [ 9888]: --> [2:OK]
>   

This says that after answering the call and sending NSF, CSI, and DIS 
that the modem did not hear any fax signal for 7 seconds.  And then...

> Oct 18 20:52:13.28: [ 9888]: <-- [9:AT+FRS=7\r]
> Oct 18 20:52:43.28: [ 9888]: MODEM <Timeout>
> Oct 18 20:52:43.28: [ 9888]: Failure to receive silence (synchronization failure).
> Oct 18 20:52:43.28: [ 9888]: <-- data [1]
> Oct 18 20:52:43.29: [ 9888]: --> [2:OK]

The modem is told to listen for 70 ms of silence (before NSF, CSI, and 
DIS are retransmitted), but for 30 seconds the modem never once hears 
that much silence.  So there was some kind of audio coming through 
constantly... but apparently not fax tones.

The Asterisk CLI output you gave was only this...

> ivr-virtual-101*CLI>
>     -- Executing [011NNNNNNNN@entrantes:1] Answer("SIP/1.2.3.4-0a096a70", "") in new stack
>     -- Executing [011NNNNNNNN@entrantes:2] Dial("SIP/1.2.3.4-0a096a70", "IAX2/125/011NNNNNNNN|15|r") in new stack
>     -- Called 125/011NNNNNNNN
>     -- Call accepted by 127.0.0.1 (format ulaw)
>     -- Format for call is ulaw
>     -- IAX2/125-14474 is ringing
>     -- IAX2/125-14474 answered SIP/1.2.3.4-0a096a70

You ended this too soon.  You need to show us what happens *after* the 
answer occurs.

Thanks,

Lee.


____________________ HylaFAX(tm) Users Mailing List _______________________
 To subscribe/unsubscribe, click http://lists.hylafax.org/cgi-bin/lsg2.cgi
On UNIX: mail -s unsubscribe hylafax-users-request@xxxxxxxxxxx < /dev/null
 *To learn about commercial HylaFAX(tm) support, mail sales@xxxxxxxxx*